The potential advantages of using diamond materials for many applications such as diamond semiconductors has spurred increasing research. Considerable research has gone into the problem of producing doped diamond devices because of this great potential. Most of the previous development work concentrated on chemical vapor deposition (CVD) with somewhat disappointing results.
Crystals of apparently pure and transparent, sp3, cubic carbon have been produced by arc deposition as a result of technology disclosed and taught by U.S. Pat. Nos. 3,625,848, Dec. 7, 1971; 3,836,451, Sep. 14, 1974; and U.S. Pat. No. 3,838,031, Sep. 24, 1974 issued to A.A. Snaper, a co-inventor of the method and apparatus disclosed herein. These patents relate to arc deposition processes and apparatus and deposition of ferroelectric material. A one millimeter (mm) laser-trimmed cube of clear, monocrystalline diamond has been produced that demonstrates that this accomplishment is feasible.
The proposed application of diamonds takes advantage of the unique properties of the crystallized carbon. These attributes include extreme hardness, durablity and unmatched ability to conduct heat and electricity. However, until the last decade or so these attributes could not be harnessed because commercial diamonds were only available from a costly process that produced diamonds as tiny clumps. Recently, however, investigators have discovered a variety of techniques for producing thin coatings of diamonds on substrates such as silicon, metals, ceramics, and even natural diamond. These new techniques have resulted in an industry wide race to be first to produce commercially valuable diamond-coated products.
These techniques have all shown the way for the development of diamond-based semiconductors. Diamonds having high thermal conductivity have a great ability to shed heat and thus diamond semiconductor chips could be positioned much closer together than their silicon based counterparts, and yet not overheat. This would allow for faster transport of electrons increasing operating speeds.
There are, however, formidable obstacles to the production of practical diamond semiconductors devices. First, semiconductors require a continuous single crystal of diamond, not separate little crystals (poly-crystalline films) that are grown with most current techniques. Further it is not easy to penetrate hard diamonds with dopants, the intentionally added impurities that make the material semiconductive. Dopants must be added during the deposition process. Conventional etching techniques used to create patterns on silicon wafers cannot be used with diamonds. Lastly, diamond films must be grown on substrates that are economical for large scale production. Continuing progress toward the production of practical diamond semiconductor devices is important because of the superior carrier mobility, thermal and photoconductivity, hardness, high temperature survivability and high voltage operating capability of doped diamond crystals which will permit an entirely new generation of useful electronic devices.
It is therefore one object of the present invention to provide a apparatus and method for producing diamond semiconductor devices.
Yet another object of the present invention is to provide an apparatus and method using plasma arc technology to produce diamond semiconductor devices.
Still another object of the present invention is to provide a method and apparatus for producing films of diamonds or "diamond-like" carbon-carbide of mostly cubic structure with precisely controlled doping.
Yet another object of the present invention is to provide a method and apparatus for depositing doped diamond in intricate patterns for integrated circuit devices such as those now being produced with silicon, germanium, gallium arsenide and other such materials.